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Full text of "The Flow Of Gases In Furnaces"

292                                   APPENDIX VII

the particle carried will increase sixty-four-fold. When the waste
gases pass down the uptakes with a high velocity they will not
make a sharp turn at the cinder pocket, but will impinge upon its
bottom, unless a considerable depth is provided. The formula of
Yesmann, giving the trajectory of the jet of flame in the furnace,
may be modified to give the distance vertically downward a flowing
jet of gas will penetrate a cooler medium, as follows:

ix/r * 


2g    tn-

English units:               H^f-

The temperature of the gases leaving the heating chamber, tm,
is 1600 (2912 F.) and U, the temperature of the gases in the
cinder pocket, is assumed as 1400 (2552 F.). The velocity of
the waste gases in the gas and air uptakes has already been
determined as 17 m 83 (58.5 ft) and 11 m 32 (37.14 ft) per second,
respectively. When these values are substituted in the above
formula, the following values of H will be found:
in gas cinder pocket ff=16 m 94 (55.58 ft)
in air cinder pocket #= 6 m 83 (22.41 ft)
Naturally, if the temperature of the immobile gases in the
cinder pocket is lower than it is assumed to be, the penetration
of the jet will be less as the difference in temperature increases.
But reducing the velocity of the waste gases will decrease the
value of Hj according to the ratio of the squares of the velocity.
Both McKune and Egler have attacked this problem and
produced head constructions which bring the air and the gas
together in a rational manner at the incoming end and provide
for an increased area of uptake at the outgoing end. Both of
these methods are radical departures from previous head con-
struction. The writer has devised a method of obtaining a
similar result and at the same time presenting the possibility of
adjusting the angle of the flame.
A large segmental air-port over a smaller gas-port is a con-
struction much favored in American furnaces. The high gas
velocity and the low air velocity result in a long flame. It was also
considered that this form of port produced a blanket of cooler